Apparatus for extracting energy from gas



Aug. 27, 1957 5, sw m 2,804,021

APPARATUS FOR EXTRACTING ENERGY FROM GAS Original Filed Sept. 29, 1949 2Sheefs-Sheet 1 (/UOJOH i Swear/fryer:

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ATTORNEYS United States Patent APPARATUS FOR EXTRACTING ENERGY FROM GASJudson S. Swearingen, San Antonio, Tex., assignor to Air ProductsIncorporated, a corporation of Michigan Continuation of abandonedapplication Serial No. 118,658, September 29, 1949. This applicationJune 27, 1955, Serial No. 518,214

17 Claims. (Cl. 103-87) This invention relates to apparatus forextracting energy from gas and has for its general object the provisionof such an apparatus which will be capable not only of extracting theenergy from the gas but also of dissipating the energy extracted withoutpermitting any substantial portion thereof to be again taken up by thegas, and without loss of gas.

It is well known that when a gas is under compression and is permittedto expand, it gives off energy. If, however, it is permitted to expandthrough an orifice, the energy given off is converted into heat much ofwhich is again taken up by the expanded gas. In order to avoid thisreabsorption of the heat energy by the gas, attempts have been made tocause the gas in expanding to do mechanical work and to transmit thismechanical work by mechanical means to some point remote from theexpanded gas and to there reconvert it into heat, so that the expandedgas will not have an opportunity to reabsorb the heat energy. Thisexpedient.can be operated with reasonable success under somecircumstances,

but under those circumstances in which relatively small volumes of gasare being handled and are being handled at pressures differingsubstantially from atmospheric pressures, the matter of transmitting themechanical energy from the turbine or other expansion engine in whichthe expanding gas does mechanical work, out of the body of expanded gasand to a remote point where it is dissipated, has been found to involvethe loss of portions of gas due to leakage about the mechanicaltransmission means, both expense and difficulty in the mechanicalconversion or absorption of the mechanical energy at the very highspeeds of rotation of these small machines, and also additional expenseand trouble with a suitable lubrication system for the high-speedbearings.

This invention has for one of its objects the provision of an apparatuswhereby mechanical energy obtained from the expansion of gas may betransmitted from the point where it is produced to another point remotefrom the body of expanded gas without the loss of gas due to leakage andwithout the loss of substantial mechanical energy due to packingfriction.

This object is attained by providing a combined bearing and pressurelubricant seal about a shaft or other mechanical work transmittingelement which transmits the mechanical energy from the zone adjacent theexpanded gas from which it is produced to a remote point where it isdissipated by means of a pump driven by the shaft to pump a liquidthrough a restricted opening and a cooler, the liquid so pumped being alubricant and being also utilized for the purpose of providing lubricantunder pressure to the bearing and seal above mentioned.

Another object is to provide such a system in which the dischargepressure of the turbine substantially exceeds the inlet pressurerequired by the pump.

Another object is to provide such an apparatus where- 2,804,02l PatentedAug. 27, 1957 in the power-absorbing means is completely enclosed sothat the problem of preventing leakage around the shaft is not alfectedby the pressure levels in the turbine.

Still another object is to provide such an apparatus which is loaded bya centrifugal pump, advantages of which are simplicity and small sizeand also the characteristic of speed variation with load in a mannerfavoring high efliciency operation of the turbine at various (turbine)inlet pressures.

Another object is to provide an arrangement whereby the pressure at theinlet to the centrifugal loading pump can be raised a substantial amountabove the pressure communicated around the shaft from the turbine. Anelevated inlet pressure is required for satisfactory operation of a highspeed centrifugal pump to suppress cavitation.

Still another object is to provide such an apparatus with aself-contained lubrication system, the load-pump fluid being thelubricant and the pump supplying it under pressure.

Yet another object of my invention is to provide such an apparatus inwhich the oil level at start is higher than during normal operation, forthe purpose of assuring the presence of oil in the pump and thrustbearing at start-up.

Another object is to provide such an apparatus whereby energy isobtained from the expansion of gas and removed therefrom, whichapparatus is simple and has few moving parts.

Other objects and advantages of this invention will become apparent fromthe following description taken in connection with the accompanyingdrawings in which are set forth by way of example and illustration oneembodiment of the invention.

In the drawings:

Fig. 1 is a view partly in side elevation, partly in cross-section andpartly in diagrammatic form illustrating an apparatus constructed inaccordance with this invention.

Fig. 2 is a longitudinal cross-section through the turbine, bearings andlubricant pump illustrated in Fig. 1, the same being on an enlargedscale. a

Fig. 3 is a transverse cross-section taken along the line 33 of Fig. 2and showing the lubricant pump.

Fig. 4 is a transverse cross-section taken along the line 44 of Fig. 2and showing the bearing and pressure lubricant seal.

Referring now more in detail to the drawings, the expansion engine whichin this instance is in the form of a gas turbine having a gas inlet 2and a gas outlet 3 has its rotor carried on a vertical shaft whichpasses downwardly through a radial bearing 4 and rests upon a thrustbearing 5 below the radial bearing. The expansion engine is enclosed bya housing, which may consist of a main turbine housing 1, a cover plate19, a depending wall sleeve 36, a bearing support housing 39, a thrustbearing support 47 and a thrust bearing 5. This thrust bearing 5, ashereinafter explained in more detail, provides the seal for preventingescape of expanded gas from the turbine without excessive packingfriction and may be considered a part of the enclosing housing as theshaft 27 may be journaled directly in thrust bearing support 47eliminating thrust bearing 5 as a separate member without sacrificingits function as a seal.

The lower end of the turbine shaft is connected to a pump generallydesignated at 6 and adapted to pump a liquid which may be used as alubricant, the rotor of this pump being held in place on the end of theshaft by means of a nut 7 or the like. The pump is adapted to dischargea liquid under pressure through its outlet 8, circulate it a through acooler 9 of any suitable design, and take the cooled liquid back inthrough the pump inlet 10.

Part of the liquid under pressure from the pump outlet 8 may be suppliedto the bearing connection 11 leading to an intermediate point on theradial bearing 4. Another connection is provided whereby part of thisliquid under pressure from the outlet 3 may be supplied to the bearingconnection 12 leading to an intermediate point of the thrust bearing 5.Lubricant forced through these two bearings, which, due to the design ofthe pump 6, is forced into the bearings under pressure greater than thatof the gas communicated from the turbine, will be collected and drawnoff through the drain connection 13 and into a reservoir 14, in whichthe pressure during operation will be that of the expanded gas in the turbine. The function of this reservoir 14 in the combination will bepresently set forth. This reservoir 14 will be filled initially to adesired level through the plugged filler opening 15, and

within the upper end of this reservoir is provided a recep taele 16Which during operation will be caused to overflow continuously into thelower end of the reservoir and which is provided With a small leak oropening 17 in or adjacent its lower end for draining it when operationceases. A connection is provided between the outlet 8 of the pump 6 andthe receptacle 16 in the reservoir 14 through a throttle valve or choke18 so that the lubricant will be constantly supplied in a small quantityto the upper end of the reservoir 14 from the outlet of the pump 8, thisquantity being greater than that which can leak through the opening 17.In order to return liquid from the reservoir to the pump in those casesin which the pressure of the expanded gas is less than the requiredinlet pressure of the pump, an, ejector arrangement is provided ashereinafter more fully described.

Referring to the structure of the turbine, bearings, and pump assemblyin still greater detail, it is noted that the main turbine housing isprovided with an upper cover plate 19 through the center of which entersthe turbine inlet 2. This plate 19 is secured tothe main housing bymeans of cap screws 20 or other suitable devices and is sealed to themain turbine housing in any conventional manner. Upon entering the mainturbine housing, gas from inlet 2 is caused to flow laterally in alldirections by the stationary deflector 21, until it reaches the annularspace 22 when it is caused to reverse its direction of flow and flowtangentially and radially inwardly toward the center of the housing 1through the stationary nozzles 23 in which itis subjected to someexpansion and its velocity increased. Emerging from these nozzles 23,the gas is conducted intothe space between the blades 24 on the turbinerotor 25, and in passing between these blades toward the axis of therotor, it is further expanded and its velocity decreased as it producesmechanical energy. The rotor 25 is mounted on the reduced upper end. 26of the vertical shaft 27 which has previously been referred to aspassing through the bearings 4 and 5. A suitable seal is providedbetween the housing 1 and the rotor 25 to separate the intermediatepressure annular zone surrounding the turbine wheel from the lowpressure zone at the turbine wheel discharge, the seal illustrated beinga carbon ring 28 carried on a flexible metallic bellows 29.

Gas, on emerging from the rotor blades 24 adjacent the hub of the rotor,is collected in the annular low pressure space 30 within the housing 1and is conducted therefrom to the turbine outlet 3.

The shaft 27 immediately below the rotor passes through a close fittingsleeve 31 disposed entirely within thehousing 1 and'carried on a plate32 which serves to close the opening in the housing 1 through which theshaft 27 passes. The sleeve 31, it will be understood, is not in tightfrictional. engagement with the shaft 27 but embraces the same with aclose tolerance. This clearance is made even closer at sub-zerotemperatures by congealed oil which may accumulate therein, and suchaccumulation acts to improve the seal, to impede ,oil flowing up theshaft into the turbine, and to impede breathing into and out of theclosed space 44 due to fluctuations in turbine pressure.

Outside of the plate 32 and the housing 1, there is a block 34 ofa'suitable thermal insulating material of substantial strength which maybe of a substance commonly known as micarta. This block likewise closelyembraces shaft 27 without frictional engagement and is held in place byone or more screws 35 passing through the plate 32. A thin wall sleeve36, preferably of metal, is fixedly secured to and depends from theturbine housing and terminates in a lateral flange 37 at its lower end.This flange in turn is secured by means of studs 38 or the like to thebearing support housing 39 and serves to support that housing. It willbe seen that the insulating block 34 will serve to provide thermalinsulation between the portion of the turbine housing 1 conducting thegas on the one hand, and the bearing support housing 39 on the otherhand. The sleeve 36, being of thin walls, will not serve to transmitmuch. heat between these parts, but by virtue of its being made integralwith the outer wall of the turbine housing and of its being secured insealing engagement with the upper end of the bearing support housing, itserves to sustain the pressure differential existing between theexpanded gases and atmospheric pressure.

With the purpose of still further insulating the turbine housing so asto prevent the absorption of heat energy by the gases contained therein,the entire turbine housing is preferably enclosed within a mass ofsuitable thermal insulating material 40.

The radial bearing 4, which is carried by the upper end portion of thebearing support housing 39, and which surrounds the shaft 27, issupplied with lubricant under pressure through the connection 11 abovementioned and through a passageway 41 formed in the body of the bearinsup ort housing 39. This lubricant passes into a groove 42 intermediatethe ends of the bearing 4, and being under a pressure greater than thepressure of the expanded gases within the turbine housing, whichpressure also exists within the sleeve 36 and the bearing supporthousing 39, this lubricant will flow in both directions from the groove42 between-the bearing 4 and the shaft 27 and provide adequate pressurelubrication for this radial bearing. Lubricant flowing upwardly alongthe shaft from this bearing will pass down into the space 44 in thebearing support housing 39 through the opening 43 provided for thispurpose while lubricant flowing downwardly along the shaft from thishearing will pass directly into the hollowspace 44 within the bearingsupport housing 39.

Within the lower end of the hollow space 44, the shaft 27 is providedwith a reduced section forming a shoulder against which is received athrust bearing collar 45 held in place onthe shaft by a set screw or thelike- This thrust collar bears against the upper surface of the thrustbearing member 5. l

The thrust bearing member 5 is supplied with lubricant under pressurethrough the connection 12 and the passageway 46 provided in the thrustbearing support 47. This passage 46 leads to an external groove 48 inthe bearing member 5, which, in turn, connects with radial passages 49through this hearing member and with an internal groove 50 in thebearing member 5 intermediate its ends.

Below the bearing member 5, the shaft 27 is still further; reduced at.51to receive the hub 52 of a pump rotor which carries impeller blades53. This rotor is held in place on theshaft by a nut or other suitablemeans.

It will be seen. that .lubricant passing fromv the groove 50 upwardlybetweenthe bearing 5 and the shaft will flow into the space 44 withinthe bearing support housing 39 and the lubricant flowingdownwardly fromthis groove 50 will flowbetween. the impeller blades 53 and join thestream of lubricant being pumped .by this rotor.

The lubricant. from, the connectionl12, being of higher pressure thanthe gas whose pressure determines the pressure in chamber 44, will flowupwardly along the shaft and between the shaft and the bearing and willthereby prevent leakage of the expanded gas from the space 44 downwardlythrough the bearing 5. The lower end of the space 44 forms a sump forcollecting lubricant from the bearings 4 and 5 and the lubricant thusdraining from the respective bearings into the space 44 will be drawnofi from this sump through the connection 13 in the manner hereinafterdescribed.

Secured to the lower face of the thrust bearing support 47 is a pumphousing 54 having an axial intake passage 55 leading upwardly insubstantial alignment with the shaft 2'7 and connected with the spacesbetween the impeller blades 53 close to the shaft. Surrounding thepassageway 55 is an annular pump discharge passageway 56 connected atits upper end with the discharge ends of the impeller blades 53 andconnected at its lower end with the pump discharge connection 8.

It will be appreciated that if the pressure of the gas in chamber 44 isgreater than the inlet pressure of the pump, the lower end of thereservoir 14 may be connected directly to the pump inlet and the gaspressure -will cause fiow from the reservoir into the pump. However, itis well known that high speed pumps require supercharging to avoidcavitation and if the inlet pressure required by the pump is greaterthan that of the expanded gas, such a simple return cannot be employed.To accomplish this return the following provision is made:

Lubricant drawn in through the inlet and passing through the passageway55 on its way to the pump rotor is caused to flow through therestriction 57 having a reduced overall cross section. A connection fromthe exterior of the pump housing is provided at 58 leading to a suctiontip 59 located within the entrance to restriction 57 and providing anannular nozzle 57a having at its outlet a zone of greatly reducedpressure which is also at the open end of the suction tip. Thus, whenlubricant is being caused to flow through the'inlet 10 and therestriction 57, it will induce flow from the connection 58, which is inturn connected to the reservoir 14.

Thus by virtue of this connection 58 the pressure in the oil reservoir,which is fixed by pressures in the turbine, is communicated to thereduced pressure zone at the out let of annular nozzle 57a. The oil athigh velocity at 57a flows through the equalizing passage 57 wherein thetwo streams, one the circulating oil from the annular nozzle 57a and theother from the suction tip 59, become intermingled as to relativevelocity. This mixing, while passing through a passage of constant crosssection, causes some overall deacceleration and consequent increase inpressure. The stream then passes into the tapered passage 55 ofgradually increasing cross section which further reduces the velocity ofthe stream and correspondingly increases its pressure. The stream fromthis tapered passage 55 enters the suction of the pump wheel. Thus apressure prevails at the pump wheel suction which is much higher thanthat prevailing at the reduced pressure zone at the outlet of annularnozzle 57a which by virtue of the connection 58 is substantially thesame as that in the oil reservoir.

While the ejector is not indispensable in cases in which the pressure atthe bearings is higher than the inlet pressure required by the pump, itis still of value in such cases. This value results from the fact thatthe oil at the bearings becomes saturated with gas and the pressure atthe bearings is the bubble point of the oil leaving the bearings. Ifsuch oil is then subjected to a lower pressure it will liberate gas.Inasmuch as oil is being constantly removed from the pump circulatingsystem and forced through the bearings and then returned after beingsaturated with gas or air at the bearings, the condition of the oil inthe circulating system will approach that of the oil from the bearingsand will have a high bubble point pressure. The use of the ejector makespossible the avoidance of a pump inlet pressure lower than the pressureprevailing at the bearings and hence avoids release of air or gas fromthe oil at a point where it might collect in the pump and cause gaslocking. The importance of this is in direct proportion to thesolubility in the lubricant of the gas expanded in the turbine.

In operation, the gas expanding and passing through the turbine, asabove described, will be discharged through the turbine outlet 3, andafter its expansion will be well insulated from taking up external heatby means of the body of insulation 40 and the insulating block 34.However, due to the fact that no complete seal is provided about theshaft 27 above the bearing 5, the pressure of the expanded gas willexist within the sleeve 36 and the bearing support housing 39.

The lubricant system illustrated more or less diagrammatically in Fig. 1will be initially filled through opening 15 until the level in reservoir14 is at a point in the neighborhood of that indicated by the arrow 60,after which the system will be closed. When the system is so filled, thelubricant will be at a level both in the reservoir 14 and in the bearingsupport housing 39 corresponding to that indicated by the arrow 60. Thesmall container 16 at the upper end of the reservoir 14 will be empty.Provision is made for equalization of pressures in the upper end of thespace 44 and in the upper end of the reservoir 14 by means of a suitablevent connection 61. The purpose of providing for the high, nonoperatinglevel at 6t) is to provide a hydrostatic head in the system sufficientto permit air or gas to be bled off from the upper end of the pumpchamber 56 through the cock 61a before starting.

After bleeding the space at the upper end of chamber 56, the apparatusmay be started, whereupon lubricant will be moved by the pump so as toflow under pressure from the pump outlet 8 and through the cooler 9, inwhich its heat energy is extracted, and back into the pump through thepump inlet 10. At the same time, lubricant under pressure (which byvirtue of the pump design is greater than the pressure of the expandedgas within the chamber 44) will be caused to flow into the bearings 4and 5 and from these bearings upwardly and downwardly along the shaft 27in the manner hereinbefore described. Also, this high pressure fluidwill be caused to flow through the choke 18 and into the upper end ofthe reservoir 14 which will be at the same pressure as the inside of thechamber 44 because of the vent line 61 above referred to. The choke 18should be of such diameter that flow will take place therethrough at arate greater than that at which the lubricant will drain out of thereceptacle 16 through the opening 17, so that this receptacle 16 willshortly become full and overflow. This will lower the level in the lowerpart of the reservoir to the point 62 and insure that space 44 will bekept drained of any lubricant Which would otherwise be beaten into afroth by the rapidly rotating shaft 27. This overflowing conditionshould be maintained throughout the operation of the device.

The lubricant flowing from the pump through the two bearings and throughthe choke 18 into the reservoir 14 will be returned to the pump throughthe ejector 59, this ejector being designed to produce a pressure at theoutlet of the suction tip 59 sufficiently low to cause lubricant to flowfrom the lower end of the reservoir 14 into the pump inlet passage 55while pressure in passage 55 is main tained high enough to avoidcavitation in the pump.

Upon shut down of operation, lubricant will drain from receptacle 16through port 17, raising the level again to point 60 to make possiblethe bleeding of the pump chamber 56 before again starting the turbine.

Since the lubricant circulation system, including the pump, the cooler,the bearings, the chamber 44 and the reservoir 14, is a completelyclosed system subjected only to the pressure of the expanded gas, andcompletely encloses the lower end of the shaft 27, it will not permitthe escape of any expanded gas. 011 the other hand, it will serve as :amechanical energy absorber to convert the mechanical energy transmittedby the shaft into heat energy in the lubricant and'to dissipate the samein the circulation of the lubricant through the cooler Withoutopportunity for the heat energy to be reabsorbed by the gas. Themechanical energy transmitted by the shaft may be converted into heatenergy in the lubricant upon the lubricant flowing through therestricted opening formed by the restriction.57, or upon the lubricantflowing through any suitable fluid flow restriction means located in thepump circuit including the cooler 9. No packing involving substantialfrictional resistance is necessary and the expanded gas is protected inevery way against reabsorption of energy.

It will be understood that the lubricant system need not necessarilyenclose the lower end of the shaft 27, it being sufficient if thissystern include a hearing or closely embracing freely fitting partsurrounding this shaft so arranged that the hearing or embracing partwill be supplied with a lubricant under pressure greater than thepressure of the expanded gas, and that means be provided for withdrawingthe lubricant flowing from this hearing or embracing part into the areaoccupied by the expanded gas without permitting the escape of expandedgas. Furthermore, an expansion engine other than a turbine and a pumpother than a centrifugal pump may be used, and for the rotating shaftthere may be substituted some other mechanical work transmittingelement.

From the foregoing, it will be seen that an arrangement has beenprovided whereby a gas may be expanded to remove energy therefrom, theenergy removed, transported to a remote point and dissipated to avoidreabsorption of the energy by the gas, and the moving parts of thedevice lubricated and sealed to prevent the escape of gas without thegeneration of excessive heat energy adjacent to the gas.

All of the other objects and advantages sought by this invention arelikewise accomplished by the means set forth, but it will be understoodthat the particular embodiment shown and described is by way ofillustration and example only and is not to be taken by wayoflimitation.

This application is a continuation of application Serial No. 118,658,filed September 29, 1949, now abandoned.

The invention having been disclosed, what is claimed is:

1. In combination, a gas expansion engine, a lubricant pump adapted todischarge lubricant at a'pressure higher than the pressure of the gas ata selected point in said engine, mechanical means including a shaftexposed to the pressure of the gas at the selected point in said engineand connecting said engine and pump whereby said engine drives saidpump, a housing enclosing said engine and a portion of said shaft andhaving a portion closely but freely embracing a zone of said shaft, aconnection be tween said pump and a point intermediate the ends of saidzone to cause lubricant to flow between said portion of said housing andsaid shaft toward said engine along said shaft to prevent flow of gasthrough said zone, means for collecting such lubricant and returning itto the inlet of said pump, means for absorbing energy from lubricantdischarged from said pump, and means connecting said pump and energyabsorbing means for circulating lubricant from the pump to the energyabsorbing means and thence back to the pump, said pump and energyabsorbing means being of such size relative to said engine thatsubstantially all of the energy derived by the engine from the expandinggas is absorbed by the pump and the energy absorbing means.

2. In combination, a gas expansion engine, a lubricant pump adaptedto-discharge lubricant at a pressure higher than the pressure of the gasat a selected point in said engine, mechanical means including a shaftexposed to the pressure of the gas at the selected point in said engineand connecting said engine and pump whereby said engine may drive saidpump, a housing enclosing said engine 'anda portionof said shaft andhaving a portion closely but freely embracing a zone of said shaft, aconnection between said pump and a point intermediate the ends of saidzone to cause lubricant to flow from said zone toward said engine alongsaid shaft to prevent flow of gas through said zone, a sump in saidhousing to collect such lubricant, a reservoir exterior of said housingand having its lower and upper end portions connected to the interior ofsaid housing at said sump and at a point spaced above said sumprespectively so as to equalize the gas pressures in said sump and insaid reservoir, and a connection between the lower end portion of saidreservoir to the inlet of said pump.

3. In combination, a gas expansion engine, a lubricant pump adapted toreceive and discharge lubricant at pressures both of which are higherthan the pressure of the gas at a selected point in said engine,mechanical means including a shaft exposed to the pressure of the gas atthe selected point in said engine and connecting said engine and pumpwhereby said engine may drive said pump, a housing enclosing said engineand a portion of said shaft and having a portion closely but freelyembracing a zone of said shaft, a connection between said pump and apoint intermediate the ends of said zone to cause lubricant to flowbetween said portion of said housing and said shaft toward said enginealong said shaft to prevent flow of gas through said zone, a sump insaid housing to collect such lubricant, a connection between said sumpand the inlet of said pump, and an ejector for drawing lubricant throughsaid last mentioned connection into the inlet of said pump.

4. In combination, a gas expansion engine, a lubricant pump adapted toreceive and discharge lubricant at pres sures both of which are higherthan the pressure of the gas at a selected point in said engine,mechanical means including a shaft exposed to the pressure of the gas atthe selected point insaid engine and connecting said engine and pumpwhereby said engine may drive said pump, a housing enclosing said engineand a portion of said shaft and having a portion closely but freelyembracing a zone of said shaft, a connection between said pump and apoint intermediate the ends of said zone to cause lubricant to flow fromsaid zone toward said engine along said shaft to prevent flow of gasthrough said zone, a sump in said housing to collect such lubricant, aconnection between said sump and the inlet of said pump, an additionalconnection between the output of said pump and the inlet of said pumpand having means therein including a restricted passage for extractingenergy from lubricant passing therethrough, the pump end of the connection from said. sump opening into said restricted passage, whereby anejector action will be produced for drawing lubricant fromsaid sump intothe inlet of said pump.

5. In combination, a gas expansion engine, a lubricant pump adapted todischarge lubricant at a pressure higher than the pressure of the gas ata selected point in said engine, mechanical means including a shaftexposed to the pressure of the gas at the selected point in said engineand connecting said engine and pump whereby said engine may drive saidpump, a housing enclosing said engine and a portion of said shaft andhaving a plurality of portions closely but freely embracing spaced zonesof such shaft and providing. bearings therefor, connections between saidpump .and an intermediate point of each of said zones to cause lubricantto flow from the intermediate points of said zones toward each end ofeach zone along said shaft, lubricant flowing in the zone most remotefrom said engine preventing escape of the gas from said engine, a sumpin said housing to catch all such lubricant flowing from all such zonesinto the housing, and a connection between said sump and the inlet ofsaid pump.

6. In combination, a gas expansion engine, a lubricant pump adapted todischarge lubricant at a pressure higher than the pressure of the gas ata selected point in said engine, mechanical means including a shaftexposed to the pressure of the gas at the selected point in said engineand connecting said engine and pump whereby said engine may drive saidpump, a housing enclosing said engine and a portion of said shaft andhaving a portion closely but freely embracing a zone of said shaft, aconnection between said pump and a point intermediate the ends of saidzone to cause lubricant to flow from said zone toward said engine alongsaid shaft to prevent flow of gas through said zone, a sump in saidhousing to collect such lubricant, a reservoir having a lower endportion lower than the bottom of said sump and an upper portion spacedabove said sump, a connection between said sump and a lower end portionof said reservoir and a connection between the interior of said housingabove said sump and an upper end portion of said reservoir respectively,a connection between a lower end portion of said reservoir and theintake of said pump, a perforate receptacle in leaking and overflowrelation to the upper end of said reservoir and a connection including arestricted passage connecting the output of said pump with saidperforate receptacle.

7. In combination, a gas expansion engine, a lubricant pump adapted todischarge lubricant at a pressure higher than the pressure of the gas ata selected point in said engine, mechanical means including a shaftexposed to the pressure of the gas at the selected point in said engineand connecting said engine and pump whereby said engine may drive saidpump, a housing enclosing said engine and a portion of said shaft andhaving a portion closely but freely embracing a zone of said shaft, aconnection between said pump and a point intermediate the ends of saidzone to cause lubricant to flow from said zone toward said engine alongsaid shaft to prevent flow of gas through said zone, a sump in saidhousing to collect such lubricant, a reservoir having a lower endportion lower than the bottom of said sump and an upper portion spacedabove said sump, a connection between said sump and a lower end portionof said reservoir and a connection between the interior of said housingabove said sump and an upper end portion of said reservoirrespectiv'ely, a connection between a lower end portion of saidreservoir and the intake of said pump, and a connection including arestricted passage connecting the outlet of said pump with the upper endof said reservoir, said reservoir including a receptacle adjacent itsupper end positioned to receive lubricant flowing from the outlet ofsaid pump through said connection with the restricted passage, saidreceptacle having a restricted drain opening adjacent its bottom topermit it to empty into the lower portion of the reservoir whenoperation of the pump ceases, and being open at its upper end into saidreservoir to overflow thereinto.

8. In combination, the components which comprise a gas expansion engine,a mechanical energy transferring means connected to said engine to bedriven thereby and extending downwardly therefrom, bearings for saidtransferring means, an absorber for mechanical energy connected to saidmechanical energy transferring means remote from and below said engineto receive energy therefrom; all of which components are in fluidcommunication with each other and sealed by an encasing structure fromexposure to a surrounding atmosphere except for the gas inlet and outletof said engine, and a liquid lubricant filling thelower part of saidencasing structure to the extent of completely filling said energyabsorber.

9. In combination, the components which comprise a gas expansion engine,a mechanical energy transferring means connected to said engine to bedriven thereby and extending downwardly therefrom, bearings for saidtransferring means, an absorber for mechanical energy connected to saidmechanical energy transferring means remote from and below said engineto receive energy therefrom and comprising a liquid pump, a liquidcooler connected to the outlet of said pump to receive liquid therefromand to the inlet of said pump to return liquid thereto, an ejectorassociated with said pump and delivering a liquid to the circuit whichincludes the pump and the cooler, all of which components are in fluidcommunication with each other and sealed against communication with theoutside except for the gas inlet and outlet of said engine, and a liquidlubricant filling the lower part of said encasing structure to theextent of completely filling said energy absorber.

10. In combination, the components which comprise a gas expansionengine, a mechanical energy transferring means connected to said engineto be driven thereby and extending downwardly therefrom, bearings forsaid transferring means, an absorber for mechanical energy connected tosaid mechanical energy transferring means remote from and below saidengine to receive energy therefrom and comprising a liquid pump, aliquid cooler connected to the outlet of said pump to receive liquidtherefrom and to the inlet of said pump to return liquid thereto, anejector associated with said pump and delivering a liquid to the circuitwhich includes the pump and the cooler, all of which components are influid communication with each other and sealed against communicationwith the outside except for the gas inlet and outlet of said engine, aliquid lubricant filling the lower part of the closed system thus formedto the extent of completely filling said energy absorber, meansconnecting said pump to said bearings to supply lubricant thereto underpressure, and means for returning lubricant thereto under pressure, andmeans for returning lubricant from said bearings to the inlet of said.pump.

11. In combination, the components which comprise a gas expansionengine, a mechanical energy transferring means connected to said engineto be driven thereby and extending downwardly therefrom, bearings forsaid transferring means, an absorber for mechanical energy connected tosaid mechanical energy transferring means remote from and below saidengine to receive energy therefrom and comprising a liquid pump, aconnection between the inlet and outlet of said pump and means providinga restricted passage in said connection, all of which components are influid communication with each other and sealed against communicationwith the outside except for the gas inlet and outlet of said engine, aliquid lubricant filling the lower part of said encasing structure tothe extent of completely filling said energy absorber, means connectingsaid pump to said bearings to supply lubricant thereto under pressure, areceptacle adjacent said bearings for collecting lubricant flowingtherefrom, and means connecting from said receptacle to said restrictedpassage and opening into the throat of said restricted passage, wherebythe flow of liquid through said restricted passage will provide anejector action to return liquid from said receptacle to said pump.

12. In combination, an elastic fluid expansion engine, a fluid pumpconnected to said engine by a mechanical means including a shaft, acommon housing around said engine, pump and mechanical means, a bean ingseated in said housing in fluid tight relationship therewith andextending to closely but freely embrace said shaft to thereby form apartition in said housing between said engine and pump and havingopposite sides thereof respectively exposed to said elastic fluid andthe discharge fluid from said pump, said pump being adapted to dischargefluid at a pressure higher than that of the elastic fluid in contactwith said bearing whereby the discharge fluid can flow along said shafttowards said engine, means connecting a sump for collecting such fluidand the inlet of said pump and energy absorbing means in fluidcommunication with the inlet and outlet of said pump, said pump andenergy absorbing means being of such size relative to the engine thatsubstantially all ofthe energy absorbed by said engine in expandingelastic fluid is absorbed by the pump and energy absorbing means.

13; In combination, a gas turbine, a lubricant pump connected to saidturbine by a mechanical means including a rotatable shaft, a housingenclosing said turbine and having an extension enclosing a portion ofsaid shaft, a bearing disposed in said extension between said turbineand pump and closely but freely embracing a portion of said shaft andforming a substantially fluid tight seal between the housing and thebearing, said bearing having a passage therethrough opening out onto itsinner bearing surface intermediate the ends of said bearing, aconnection between the outlet of said pump and said bearing to introducelubricant into said passage to flow along said shaft toward saidturbine, a sump in said housing to catch such lubricant, a reservoirexterior of said housing and having a lower end portion lower than thebottom of said sump and an upper end portion spaced higher than saidsump, a connection between said sump and said lower end portion of saidreservoir, a connection between the lower end por tion of said reservoirand the inlet to said pump, a receptacle connected to overflow into saidreservoir and having a restricted drain adjacent its bottom into saidreservoir to permit it-to empty into said reservoir when operation ofthe pump ceases, and a connection including a restricted passage betweenthe outlet of said pump and said receptacle.

14. In combination, a gas turbine, a lubricant pump connected to saidturbine by a mechanical means including a rotatable shaft, a housingenclosing said turbine and having an extension enclosing a portion ofsaid shaft, a bearing disposed in said extension between said turbineand pump and closely but freely embracing a portion of said shaft .andforming a substantially fluid tight seal between the housing and thebearing, said bearing having a passage therethrough opening out onto itsinner bearing surface intermediate the ends of said bearing, aconnection between the outlet of said pump and said bearing to introducelubricant into said passage to flow along said shaft toward saidturbine, a sump in said housing to catch such lubricant, a reservoirexterior of said housing and having a lower end portion lower than thebottom of said sump and an upper end portion spaced higher than saidsump, a connection between said sump and said lower end portion of saidreservoir, a connection between the lower end portion of said reservoirand the inlet to said pump, a receptacle connected to overflow into saidreservoir and having a restricted drain adjacent its bottom into saidreservoir to permit it to empty into said reservoir when operation ofthe pump ceases, a connection including a restricted passage between theoutlet of said pump and said receptacle, and an ejector for drawinglubricant from said reservoir and discharging the same to the inlet ofsaid pump.

15. In combination, an elastic fluid expansion engine, a fluid pump,mechanical means including a shaft connecting said engine to said pumpfor driving the latter, a closed fluid circulation system connectedbetween the discharge and inlet of said pump, means connected in saidsystem for absorbing energy from the fluid being circulated, said pump,and energy absorbing means being.

of such size relative to. said enginethat substantially all of theenergy removed fromsaid elastic fluid by said engine is absorbed by thepump and said energy absorbing.

16. In combination, an elastic fluid expansion engine,

operable to remove energy from elastic fluid. upon expansion of elasticfluid in'the engine, a fluid pump having a discharge and an inlet, ashaft directly connecting the.

engineto the fluid pump for drivingrthe pump by the energy removed. fromthe elastic fluid, a closed fluid system connected betweenthe dischargeand inlet of the pump through which fluid is circulated upon operationof the pump, means for transferring to the fluid being circulated in theclosed fluid system the major portion of the energy removed from theelastic fluid, energy absorbing means included in the closed fluidsystem for absorbing substantially the total energy transferred to thefluid being circulated through the closed fluid system, and means alongsaid shaft providing a sealing fluid therearound for preventing elasticfluid flow from said engine along said shaft.

17. In combination, an elasticfluid expansion engine operable to removeenergy from elastic fluid upon expansion of elastic fluid in the engine,a fluid pump having a discharge and an inlet, a shaft directlyconnecting the engine to the fluid pump for driving the pump by theenergy removed from the elastic fluid, a closed fluid system connectedbetween the discharge and inlet of the pump through which fluid iscirculated upon operation of the pump, fluid flow restriction meansincluded in the closed fluid system to load the pump and transfer to thefluid being circulated in the closed fluid system a major portion of theenergy removed from the elastic fluid, energy absorbing means includedin theclosed fluid system for absorbing substantially-the total energytransferred to the fluid being circulated through the closed fluidsystem.

References Cited in the file of this patent UNITED STATES PATENTS1,337,098 Standerwick Apr. 13, 1920 1,474,086 Poebing Nov. 13, 19231,476,781 Vincent' Dec. 11, 1923 1,787,088 Schleyer Dec. 30, 19302,030,474 Schmidt Feb. 11, 1936 2,124,395 Caughey July 19, 19382,159,422 Buchi May 23, 1939 2,608,380 Rice Aug. 26, 1952

